Degasser device



Jan. 21, 1969 Filed June 2, 1967 I M/VEIVTO/P. MCI/0045 NAPO/PA MMM United States Patent 3,422,857 DEGASSER DEVICE Nicholas Napora, Pittsburgh, Pa., assignor to Dresser Industries, Inc, Dallas, Tex., a corporation of Delaware Filed June 2, 1967, Ser. No. 643,121 US. Cl. 138-143 Int. Cl. F161 9/14; C21c 7/10 8 Claims ABSTRACT OF THE DISCLOSURE As the requirement for metals with improved properties has continued to increase, the metals industry has had to turn to more contemporary techniques to improve the product. One such technique is to remove entrapped gases that are acquired by the metal during the refining process. Generally speaking, these gases can cause brittleness in the metal. Techniques and equipment for removing these gases while the metal is still molten are several. One apparatus, for example, is known as the D-H degasser. In this apparatus, an enclosed vacuum chamber with a conduit attached in open communication with its base is positioned over a ladle of molten steel. The conduit is immersed in the molten steel, a vacuum drawn upon the chamber and molten metal rushes up through the conduit into the chamber releasing entrapped gases After the chamber is nearly filled, the ladle is lowered and the molten metal returns to the ladle. This process is often repeated many times before the desired low gas level is obtained.

In another type of degassing apparatus, two conduits are attached in open communication with the base of the degassing chamber. The metal is drawn up through one conduit and returned to the ladle through another.

. Conduits joining degassing chambers and ladles have been constructed of a combination of refractory brick and monoliths, mortar and metal. A metal pipe or conduit forms the skeleton or support against which the refractories are placed. Heretofore, the metal pipe has usually been coated with monolithic materials to protect the pipe during immersion in the molten metal. Conduits of this type have not been altogether successful. One disadvantage results primarily from differences in coefficient of thermal expansion between the metal and refractory monolith; that is, the metal pipe expands when heated while the castable or monolithic coating shrinks as it dries up. This leads to cracking of the refractory and failure. An outer layer of refractory brick about the metal support cylinder was suggested but not actually pursued since no suitable means had been discovered to prevent the brick lining from shifting position and falling apart. Also, a base support must be provided to hold all of the components, i.e., concentric rings of refractory and metal support, in their relative positions during use.

Accordingly, it is an object of this invention to provide a device for degassing molten metal having a snorkel for drawing molten metal into the degassing chamber, which 3,422,857 Patented Jan. 21; 1969 snorkel is not easily eroded by the washing action of molten metal and slags, which is not susceptible to spalling caused by rapid change in temperatures, which does not react with metal, which is nearly impermeable and which has a tight structure, i.e., one which does not develop free play between parts easily.

Another object of the invention is to provide a snorkel for vacuum degassers having an outer lining of refractory brick and means for supporting said lining and the interior linings of the metal support.

In order to more fully understand the nature and scope of the present invention, reference should be had to the following detailed description and drawings, in which:

FIG. 1A is an elevation view partly in cross-section of a portion of a vacuum degasser and snorkel according to the present invention;

FIG. 1B is an elevation view partly in cross-section of the snorkel of FIG. 1A;

FIG. 2 is a plan view taken along line 2-2 of FIG. 1B; and

FIG. 3 is a perspective view of a refractory shape for use in the support ring at the base of the snorkel.

In accordance with the present invention, there is provided a conduit for transferring molten metal from one vessel to another by providing a differential pressure. The conduit is composed of a plurality of concentric cylindrical members. Beginning from the interior, there is an inner cylinder composed of courses of highly refractory shapes.

There may be one or more cylinders of insulating material contiguously surrounding the major extent of the inner cylinder. The insulating material can consist entirely of refractory insulating brick, a monolithic insulating lining or a combination of either with or without an insulating material, such as, asbestos.

Surrounding the major extent of the cylinder of insulating material is a metal support cylinder which contains an inwardly extending peripheral flange at the lower end to support at least the cylinder or cylinders of insulating material. The metal cylinder also contains a plurality of outwardly extending flanged projections disposed at spaced intervals along the outer periphery thereof.

The inwardly extending flange contains a plurality of hanger members projecting below the lower end of the conduit. The hanger members are disposed soldier-style along the bottom surface of the flange for engaging refractory shapes in the bottom support ring.

An outer cylinder, composed of courses of highly refractory shapes, surrounds the metal support cylinder. These shapes contain one or more slots for the reception of the flanged projections to prevent horizontal movement.

A bottom rim or ring composed of a plurality of abutting refractory shapes are attached to the lower end of the conduit. The shapes are provided with means for engagement with the hanger members to hold them in place. Each shape is characterized as having a relatively flat upper surface and opposed side walls. The shapes extend from the inner periphery of the conduit to the outer periphery. The flat upper surfaces of the shape are in contiguous contact with the refractory shapes at the lower end of the conduit in the inner and outer cylinders to provide support therefor.

Referring to the drawings, there is shown a snorkel 10 according to the present invention. The body (see FIG. 1A) of a vacuum degasser has an opening in its floor, 12. Connected in open communication with the degassing chamber is the snorkel 10. The snorkel or conduit is comprised of a plurality of concentric cylinders. There is an inner cylinder 14 fabricated from materials, such as, high purity dead burned magnesite shapes, fused grain magnesite chrome shapes a d others. Contiguously surrounding the inner cylinder of refractory shapes is a cylinder 16 of insulating brick shapes. Adjacent the cylinder of insulating brick shapes is a cylinder 18 of a compressible material, for example, asbsetos. A metal support cylinder 20 surrounds the cylinder of compressible material. It contains an inner peripheral flange 22 at the lower end thereof which supports the asbestos and insulating brick cylinders 18 and 16 and a portion of the inner cylinder 14, if desired. An outer cylinder 24 composed of courses of highly refractory brick surrounds the metal support cylinder. These shapes are preferably composed of a burned high alumina brick. A suitable brick is that described and claimed in United States Patent 3,067,050 to Miller, assigned to the present assignee. These shapes may contain, as shown in the drawings, on all surfaces in contact with adjacent brick, complementary tongues and grooves for interlocking with the adjacent shapes. The shapes also contain a slot 26 for reception of the projecting flanges 28 of a T-bar 30 which is secured, at spaced intervals, to the outer periphery of the metal support cylinder 20 (see FIG. 2).

The inwardly extending flange 22 of the metal support cylinder contains a plurality of substantially parallel metal plates 32 extending downwardly from the flange. Each plate contains outwardly extending lugs 34 for engaging refractory shapes disposed between each pair.

A rim 36 comprised of refractory shapes such as high alumina shapes set forth above, is disposed at the lower end of the conduit. Each of the shapes 33 (see FIG. 3) in the rim 36 are generally characterized as having a relatively flat upper surface .0, a lower surface 42 and opposed side walls 44 joining the upper and lower surfaces. As shown in FIG. 3 the lower surface 42 is arcuate; however, other configurations may be employed. The opposed side walls of the shape have a complementary cut out 46 extending from the upper surface downwardly a portion of the distance of the side walls and terminates at a base 48. The side wall in the cut-out is defined by alternate mortise-like depressions 50 and tenorlike projections 52. The mortise-like depressions extend from the upper surface 40 to the base 48. The tenor-like projections extend from the upper surface 40 to a point short of the base to provide recesses 54. The metal plates are disposed within the cut-out with the inwardly extending lugs 34 engaging the recesses.

The above snorkel is fixed at its upper end 56 in open communication with a chamber for removing gases from metal. The lower end is positoned for immersion into a ladle containing the molten metal.

The advantages of the construction outlined above over the prior art are several. There is provided a tight structure with no open spaces, which structure remains tight upon heating and cooling. The inner lining is comprised of a basic brick which has almost no tendency to react with molten metal and is very refractory, thereby greatly reducing the tendency to be eroded by the molten metal. The portion of the conduit receiving the most extreme abrasion is the outer refractory lining and the rim. These are suitably constructed of very dense, high alumina refractory brick known for their resistance to abrasion. The insulating layers provide a shallow thermal gradient through the inner refractory cylinder thereby reducing its tendency to spall. Second, the insulating layer maintains the metal cylinder at a temperature sutflciently low that it does not loose its structural srength required to support and contain the whole conduit. The compressible layers allow for different expansion between the metal cylinders and the enveloped refractory cylinder and at the same time maintain a tight structure. The outer cylinder of refractory brick protects the outer surface of the metal shell.

While the conduit described above has been discussed in relationship with a degassing vessel, it is obvious that it is of use in transferring molten metal from one vessel to another by any process whereby the metal is transferred by a differential pressure.

Having thus described the invention in detail and with suflicient particularity as to enable those skilled in the art to practice it, what is desired to have protected by Letters Patent is set forth in the following claims.

I claim:

1. A conduit for transferring molten metal from one vessel to another by providing a differential pressure, the conduit being fabricated from a plurality of concentric cylindrical members including:

(a) an inner cylinder composed of highly refractory material;

(b) at least one cylinder of insulating material contiguously surrounding the major extent of said inner cylinder;

(c) a metal support cylinder adjacently surrounding he major extent of the cylinder of insulating material, said cylinder having an inwardly extending peripheral flange at the lower end thereof supporting at least the cylinder of insulating material, said inwardly extending flange having a plurality of hanger members projecting below the lower end of the conduit, said hanger members being disposed soldierstyle along the bottom surface of the flange for engaging a refractory shape disposed thereat;

(d) an outer cylinder composed of courses of highly refractory shapes surrounding the metal support cylinder; and

(e) a bottom rim composed of a plurality of abutting refractory shapes attached to the lower end of the conduit, said shapes being provided with means for engagement with the hanger members to hold them in place, each shape being characterized as having a relatively flat upper surface and opposed side walls, the shapes extending from the inner periphery of the conduit to the outer periphery, the flat upper surfaces thereof being in contiguous contact with the refractory shapes at the lower end of the conduit in the inner and outer cylinders to provide support therefor.

2. A conduit according to claim 1 in which the metal cylinder contains a plurality of outwardly extending flanged projections disposed at spaced intervals along the outer periphery thereof.

3. A conduit according to claim 2 in which the shapes in the outer cylinder contain at least one slot for reception of the flanged projections to prevent horizontal movement thereof.

4. The conduit of claim 1 in which the hanger means projecting downwardly from the inwardly extending flange consists of a plurality of substantially parallel metal plates, each plate containing outwardly extending lugs for engaging a refractory shape disposed between a pair of plates and in which the opposed side walls of the abutting refractory shapes contain complementary cutouts extending from the upper surface downwardly to a base and the cut-out portion of the side wall contains recesses therein, said metal plates being disposed within .the cut-outs with the outwardly extending lugs engaging the recesses.

5. A conduit according to claim 1 in combination with a device for degassing molten metal comprised of a ladle for containing molten metal, a chamber for removing gases from said metal, the chamber being positioned above the ladle, in which the conduit is fixed in open communication at its upper end to the chamber and is positioned for immersion of its lower end into the ladle.

6. The conduit of claim .1 in which the refractory shapes in the outer cylinder are provided with interlocking means to further restrict horizontal movement.

7. The conduit of claim 1 in which each of the refractory shapes in the outer cylinder contain a flange receiving slot on opposed ends.

8. A refractory shape suitable for use in the bottom rim of a snorkel for vacuum degasser vessels, having a relatively flat upper surface, a lower surface and. opposed side walls joining the upper and lower surfaces, the 0pposed side walls having a complementary cut-out extending from the upper surface downwardly a portion of the distance of said side walls and terminating at a base, the side wall in said cut-out being defined by alternate mortise-like depressions and tenor-like projections, the mortise-like depressions extending from the upper surface to the base, the tenor-like projections extending from the upper surface to a point short of the base to provide recesses.

6 References Cited UNITED STATES PATENTS 3,203,688 8/ 1965 Sieckman et a1.

3,337,329 8/1967 Finkl 7549 3,353,809 11/1967 Snellman 26638 X 3,384,362 5/ 1968 Philbrick 75-49 X LOUIS K. RIMRODT, Primary Examiner.

US. Cl. X.R. 

